1. Field of the Invention
The present invention relates to multiple point focus detection cameras that perform the action of focussing based on focus detection data measured in selected focus detection areas from among a plurality of available focus detection areas.
2. Description of Related Art
Under the prior art, in a camera equipped with a focus detection device, as shown in FIG. 10, a focus detection area 8 has been provided in the center of the field of vision 9 of the viewfinder. Focus detection is performed in the focus detection area 8, and the lens is moved so as to focus the lens on the subject in the focus detection area 8.
However, in cases where the focus detection area 8 is in the center of the field of vision 9 of the viewfinder, such as is shown in FIG. 10, but the primary subject that the photographer wants to photograph is not in the center of the field of vision 9 of the viewfinder, a photograph is taken with the camera focussed on something other than the primary subject.
As shown in FIG. 11, a camera has also been proposed that has a structure such that a plurality of focus detection areas 8 are provided in the field of vision 9 of the viewfinder, from among which a specific area is selected, the lens being focussed according to the subject in the area selected. Two methods are known for deciding in the camera which area is to be selected from among the plurality of focus detection areas 8. First, there is a method wherein the selection of one of the focus detection areas from among the plurality of focus detection areas 8 is received from the photographer, focus detection being performed on the focus detection area received, and the lens being focussed on the subject in the area. There is another method wherein focus detection is performed in all of the multiple point focus detection areas 8, the area containing the primary subject being automatically selected through computations based on the processing of the obtained focus detection data under predetermined or user-selected criteria, and the lens being focussed on the subject in the selected area. In this instance, the criteria used to automatically determine the focus detection area could be, for instance, the selection of the focus detection area having the shortest distance from the camera. Conventionally, the former of these two methods is called the manual mode and the latter is called the automatic mode. A camera has been known which is equipped with both methods so that either can be used at the discretion of the photographer.
The manual mode described above emphasizes the composition of the photographer and has the advantage of allowing photographs to be taken according to the will of the photographer. However, because the camera focusses on an area that has already been set, there is the fear that a photograph could be taken that is not focussed on the primary subject if the photographer were to forget that the camera is set in the manual mode.
On the other hand, with the automatic mode, there is the fear that when a special composition is desired, the camera could focus on something other than what the photographer desires to be the primary subject.
In addition, because photography involving the use of a self timer is frequently used, especially for commemorative photographs that cannot be retaken later, it is desirable to take photographs after making certain of the subject being focused upon. However, in most cases involving the average photographer, and normally for professionals and advanced amateurs, a photograph focussed on the primary subject can be taken in the automatic mode without error. Accordingly, in considering the case where a multiple point focus detection camera is used by a novice, the manual mode would hardly ever be used; accordingly the automatic mode can be assumed to be more frequently used for photography.
In addition, when the same camera is used by a number of different individuals, there would be the concern that if the prior user were to leave the camera in the manual mode and a photograph were taken without noticing this setting, a picture could result that is not focussed on the primary subject. In that case, because the user usually realizes that the photograph was taken using the manual mode only after the prints have been made, there are many cases where the photograph cannot be retaken. In order to prevent this kind of error, it is necessary to verify the mode that was set previously each time a photograph is taken. It is desirous to eliminate this necessity.